A highly controversial portrait believed by some art experts to be a "younger version" of the Mona Lisa currently hanging in the Louvre will be displayed today in Geneva to coincide with the publication of a book claiming it was painted by Leonardo da Vinci over a decade earlier.

The so-called "Isleworth Mona Lisa" was discovered nearly a century ago by British collector Hugh Blaker and has since changed hands twice before being purchased by an anonymous international consortium.

Teaming up with art experts to form the Mona Lisa Foundation, the painting's owners aim to prove the "Isleworth Mona Lisa" was painted by da Vinci 11 or 12 years before the version art afficiandos have come to know and love.

"So far, not one scientific test has been able to disprove that the painting is by Leonardo," art historian Stanley Feldman told the Associated Press.

Feldman is a member of the foundation and the lead author of Mona Lisa: Leonardo's Earlier Version.

"When we do a very elementary mathematical test, we have discovered that all of the elements of the two bodies - the two people, the two sitters - are in exactly the same place," he said. "It strikes us that in order for that to be so accurate, so meticulously exact, only the person who did one did the other ... It's an extraordinary revelation in itself, and we think it's valid."

But other experts aren't so sure.

Da Vinci specialist Martin Kemp of Oxford University said that, just as Leonardo's hand in the painting can't be disproved, it similarly can't be definitively proved.

"‬So much is wrong," he told The Sunday Times. "The dress,‭ ‬the hair and background landscape.‭ ‬This one is also painted on canvas,‭ ‬which Leonardo rarely did. She might look younger but this is probably because the copyist,‭ ‬and I believe it is a copy done a few years after the Mona Lisa,‭ ‬just painted it that way."